The present invention relates to a method and system of CDMA (Code Division Multiple Access) communication, for example, specified by North America EIA/TIA standard as IS-95.
Conventionally, an analog cellular system uses Frequency Division Multiple Access (FDMA), in which FDMA channels are defined by a range of radio frequencies, usually expressed in a number of kilohertz (kHz), out of the radio spectrum. In recent years, digital communication methods, such as TDMA and CDMA, have been used for mobile communication. TDMA (rime Division Multiple Access) communication method is specfied, for example, by North American TIA/EIA standard as IS-136. CDMA (Code Division Multiple Access) communication method is specified, for example, by North American EIA/TIA standard as IS-95. Especially, CDMA communication method is expected to be the most useful and popular method for mobile communication.
The CDMA communication method has many advantages as compared to the conventional analog method, in that the frequencies can be used efficiently. According to the CDMA technique, however, it is difficult for a mobile station to reduce power consumption in an idle state (waiting state). This is because, the mobile station performs many processes in the idle state.
Accordingly, an object of the invention is to reduce the power consumption of a mobile station.
Additional objects, advantages and novel features of the invention will be set forth in part in the description that follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
According to a first aspect of the invention, in a method of CDMA communication, a page message notice signals transmitted over a page message notice channel that is different from paging channels. The page message notice signal indicates whether a monitor-required page message is included in an up-coming time slot.
In the method of CDMA communication, each mobile station monitors the page message notice channel, and monitors the assigned paging channel only when the page message notice signal indicates that the up-coming time slot includes a monitor-required page message addressed to the mobile station.
According to a second aspect of the invention , a CDMA communication system includes a base station which transmits page messages over a plurality of paging channels, and a page message notice signal over a page message notice channel that is different from the paging channels. The page message notice signal indicates whether a monitor-required page message is included in an up-coming time slot transmitted N slots later than the current time slot. The system also includes mobile stations each of which monitors the page message notice channel, and monitors a certain assigned paging channel only when the page message notice signal indicates that a monitor-required page message is included in the up-coming time slot assigned to the mobile station.
In the CDMA communication system, each mobile station may includes a CPU which processes the page message; a baseband-processing unit which processes the page message notice signal; and a control circuit which controls the CPU and the baseband-processing unit. In this case, the control circuit controls the CPU so that the CPU does not wake up for operation until the page message notice signal indicates that a monitor-required page message is included in the up-coming time slot assigned to the mobile station.
According to a third aspect of the invention, a CDMA transmitter includes a page message generator which generates page messages to be transmitted over a plurality of paging channels. The transmitter also includes a notice signal generator which generates a page message notice signal to be transmitted over a page message notice channel that is different from the paging channels. The page message notice signal indicates whether a monitor-required page message is included in an up-coming time slot transmitted N slots later than the current time slot.
According to a fourth aspect of the invention, a CDMA receiver includes a CPU which processes the page message; a baseband-processing unit which processes the page message notice signal; and a control circuit which controls the CPU and the baseband-processing unit. In the CDMA receiver, the control circuit may control the CPU so that the CPU does not wake up for operation until the page message notice signal indicates that a monitor-required page message is included in the up-coming time slot assigned to the mobile station.